1. Field of the Invention
The present invention relates to the field of mechanical techniques, and in particular to a crane and automated storage and retrieval system (AS/RS).
2. The Related Arts
In AS/RS, the crane is used for moving cassette inside the AS/RS. Specifically, the movement of a crane comprises: moving the cassette from the temporary location of the upstream moving system into AS/RS system, moving the cassette to temporary locations of a plurality of processing machines, moving cassette loaded with processed goods into AS/RS, and moving cassette to the temporary location of the downstream moving system.
Referring to FIG. 1, FIG. 1 is a schematic view showing the structure of a known crane. As shown in FIG. 1, a known crane 10 comprises a horizontal transmission mechanism 101, an arm 102 and a vertical transmission mechanism 103, wherein the horizontal transmission mechanism 101 comprises four wheels 111 and a guiding mechanism 112. Under the guidance of guiding mechanism 112, wheels 111 move the arm 102 and the vertical transmission mechanism 103 along the horizontal direction. The vertical transmission mechanism 103 moves the arm 102 along the vertical direction.
Because the crane 10 is only disposed with an arm 102, only one cassette can be moved at one time. When a plurality of cassettes needs to be moved, additional movement process must be executed. Therefore, the efficiency is too low to meet the requirement of the increasing moving demands.
In addition, the horizontal transmission mechanism 101 uses wheels 111 to roll in combination with the guidance of the guiding mechanism 112 to realize the horizontal movement of the arm 102 and the vertical transmission mechanism 103. As the wheel 111 is prone to skidding, the stability of the crane 10 may be compromised.